Typically, tape guide rollers are needed to control the longitudinal movement of tape along a tape path which varies from a straight line. One example is a tape path for a magnetic tape that extends between tape reels and across a magnetic tape head which is configured to read and/or write magnetic signals with respect to the magnetic tape.
The arrangement of the tape reels is typically such that the tape reels are in the same plane, but are also at angles with respect to the tape path across the magnetic tape head. In addition, the angle of the tape as it is fed from one reel and as it is fed to another reel may be constantly changing. Thus, the tape is wrapped around the tape guide roller to allow longitudinal movement of the tape in which the longitudinal direction of the tape is changed from the direction to or from a tape reel to the tape path across the magnetic tape head.
Typically, such tape guide rollers have smooth cylindrical surfaces on which the tape is wrapped, and may have flanges to maintain the lateral alignment of the tape. Such tape guide rollers may have ball bearings or roller bearings to support the tape guide roller “barrel” and to reduce friction and allow rotation, but also have an intrinsic resistance to spin on their axes due to viscous drag of the bearings. An air film may form between the cylindrical surface and the tape, and due to the tape guide roller's resistance to spin, dissimilar speeds may result between the tape guide roller and the tape. The result is that the edges of the tape may contact a flange of the tape guide roller while at dissimilar speeds. Dissimilar speeds in turn may create the condition that the edges of the tape act like abrasive blades that scar the flanges. Flange scarring may result in transient disturbances to the lateral position of the tape and perhaps prevent a track following servo from correctly following the tracks of the magnetic tape, degrading performance. Dissimilar speeds may also cause excessive production of tape debris.